Method and apparatus for measuring and monitoring a power source

ABSTRACT

A system and method for monitoring batteries is disclosed. There is provided a plurality of sensors each adapted to communicate with one of the batteries, and to provide information concerning a characteristic of the battery in response to application of a stimulus to the battery. A controller that communicates with the sensors is also provided. In one embodiment, the sensor includes the battery.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. application Ser. No.13/169,907, filed Jun. 27, 2011, now U.S. Pat. No. 8,311,753 which is acontinuation of U.S. application Ser. No. 12/089,745, filed Aug. 26,2008, now U.S. Pat. No. 7,970,560, issued on Jun. 28, 2011, entitled“METHOD AND APPARATUS FOR MEASURING AND MONITORING A POWER SOURCE,”which is a national stage application of PCT Application NumberPCT/US2006/039987 filed Oct. 11, 2006, which claims priority to U.S.Provisional Application No. 60/725,244 filed Oct. 11, 2005, thedisclosures of which are incorporated herein by reference in theirentireties.

BACKGROUND

Generally the communications and computing equipment intelecommunication central offices, datacenters, and wireless networkcell sites require a −48V DC (direct current) or −24V DC power source,and some data equipment require AC power. Typically, the commercial ACpower feed that supplies a site is converted to DC to appropriatelymatch the requirements of the individual equipment.

Because commercial AC power is not always reliable enough fortelecommunication systems and mission critical business informationsystems, it is common to provide backup power in the event of a failureof the commercial feed. The backup power is typically provided by acollection of power sources or electrochemical batteries, known as abattery plant. The batteries may be located within an uninterruptiblepower supply (UPS) or centrally located within the site and coupled withpower distribution bars, to feed DC equipment, and inverters, to feed ACequipment. Regardless of where the batteries are located, they are oftenoriented in groups, wired in series up to a required voltage.

In order to obtain the maximum battery run-time and life expectancy, itis necessary to perform periodic maintenance tests. These tests arecommonly performed by maintenance personnel who travel to the remotesite and, using complex and expensive equipment, take measurements andreadings from the batteries. This work is made more difficult when thesites are located in remote geographic areas. In order to increasebattery plant reliability and lower maintenance costs, it is desirableto perform these tests more often and perhaps without physicallydispatching maintenance personnel.

SUMMARY

The disclosed embodiment includes a system for monitoring a powersource, such as a battery that includes:

-   -   a voltage regulator;    -   a. an electronic switch;    -   b. a temperature sensor;    -   c. an amplifier;    -   d. an analog to digital converter; and,    -   e. a micro-controller;    -   wherein:    -   f. the voltage regulator is adapted to receive power from a        battery to be monitored and is coupled to at least the        micro-controller, the amplifier and the analog to digital        converter to provide a regulated voltage thereto;    -   g. the microcontroller is adapted to generate switching        commands, for application to the electronic switch, according to        a program;    -   h. the electronic switch is adapted to receive the switching        commands and to apply a stimulus to the battery in accordance        with the switching commands;    -   i. the temperature sensor is adapted to measure a temperature of        the battery and provide a temperature signal indicative thereof;    -   j. the amplifier is adapted to receive a signal from the battery        in response to application of the stimulus, defining a response        signal;    -   k. the analog to digital converter is adapted to receive the        temperature signal and the response signal and provide digital        indications thereof to the micro-controller;    -   l. there being information in the sensor that is available when        the sensor has been installed in a connected string of batteries        to be monitored that is useful to determine a relative position        of the sensor in the connected string of batteries, defining        location information, wherein each sensor is adapted to be        associated with one of the batteries; and,    -   the microcontroller being further adapted to: (i) process at        least the digital indication of the response signal according to        the program; (ii) generate data indicative of at least one        condition of the battery; and, (iii) report the data indicative        of the at least one battery condition and data indicative of        battery temperature and the location information.

A corresponding method for monitoring a power source, such as a battery,is also disclosed.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a circuit diagram of a battery model;

FIG. 2 is a circuit diagram of battery model test circuit;

FIG. 3 depicts a typical discharge profile;

FIG. 4 is a circuit diagram of an exemplary remote measurement sensor;

FIG. 5 depicts a perspective view of a remote measurement sensor withbattery;

FIG. 6 depicts a remote measurement system;

FIGS. 7A and 7B illustrate a remote measurement sensor in perspectiveand “x-ray” views, respectively;

FIG. 8 depicts a perspective view of a site control unit; and

FIG. 9 is a functional flow of sensor unit operation.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

FIG. 1 is a circuit diagram of the Randles battery model 100. TheRandles battery model 100 is a mathematical battery model thatcharacterizes the electrical properties and behavior of a real battery.The Randles battery model 100 is a commonly accepted simplified model ofan electrochemical battery. It consists of an ideal voltage source (Vb)101, a resistance element (Ri) 102 connected in series to the positiveside of Vb 101, a capacitive element (C) 104 in parallel with Vb 101 andRi 102, and a resistance element Rm 103 connected at one node to both Ri102 and C 104. Connected to the opposite side of Rm 103 is a positivenode 105. Connected to the negative side of Vb 101 and C 104 is anegative node 106.

The Randles battery model is only one of many acceptable battery models.Other arrangements of Ri 102, Rm 103, and C 104 are sometimes used, butthe resultant performance can be shown to be roughly equivalent. Thedisclosed embodiments contemplate other battery models, the Randlesbattery model is presented as an example.

In this model, Ri 102 represents an equivalent internal resistanceattributable to the voltage source. Rm 103 represents the resistance dueto metallic connections. In addition to these resistances, there may bean equivalent internal capacitance represented by C 104. In practicalapplications of lead-acid batteries with capacities of 100-200ampere-hours, Ri 102 and Rm 103 may be roughly equal with a combinedresistance typically in the range of 0.1 milliohm to 1.0 milliohm, and C104 is typically in the range of 1.0 to 2.0 Farads per 100 ampere-hoursof capacity.

It is possible to calculate the values of the Randles model, and otherbattery models, by applying and then removing a DC load of known currentwhile observing the time-dependent voltage change at the batteryterminals. FIG. 2 is a circuit diagram of exemplary battery model testcircuit based on the Randles model.

In FIG. 2, a fixed external resistive load Rt 201 in series with aswitch 202 may be applied between the positive node 105 and the negativenode 106. When the switch 202 is in the open position C 104 may chargeto a voltage equivalent to that of Vb 101. The switch 202 may be closedat a time t0, and C 104 may supply an instantaneous current (It) 203generally consistent with the following:

${It} = \frac{Vb}{{Rm} + {Rt}}$

If Rt 201 is selected to be very large compared to any expected value ofRm 103, then the value of It 203 may be simplified to:

${It} = \frac{Vb}{Rt}$

The value of It 203 over time may be used to develop a dischargeprofile. FIG. 3 depicts a exemplary discharge profile 300. The profile300 shows the value of voltage Vt as measured between positive node 105and negative node 106 over time after t0. Phase I 301 of the dischargeprofile represents the instantaneous drop in voltage Vdelta1 that may becalculated by:Vdelta1=2·It·Rm

After the Phase I 301 discharge interval, the voltage Vt will continueto drop in the well-known exponential manner of RC circuits until asteady-state value of Vt is reached. This exponential discharge periodis depicted in the discharge profile as Phase II 302 discharge. Theamount of voltage drop during this interval is Vdelta2 and may becalculated as a function of the values of Ri 102, Rm 103, and It 203:Vdelta2=It·(Rm+Ri)

It may be assumed that Rm 103 is approximately equal to Ri 102. As aresult, the calculation for Vdelta2 may be simplified to:Vdelta2=2·It·Rm

Note that Vdelta2 may be approximately equal to Vdelta1. After thecompletion of the Phase II 302 discharge interval, Vt may continue todecline at a much slower rate due to depletion of the surface chargewhich is characteristic of lead-acid batteries. The rate of decline ofVt during this period is depicted as Phase III 303 discharge. It isreasonable to assume throughout the Phase III 303 interval, the changeof Vt may be essentially linear over short time intervals. After thePhase III 303 surface charge depletion interval is complete, the batterymay then enter an interval of long-term discharge depicted as Phase IV304 discharge.

The characteristics as calculated by a battery model may be used tocharacterize the battery's internal parameters. Such a characterizationmay be used to establish a set of metrics which may be indicative of thebattery's health and the battery's ability to deliver power to a load.

FIG. 4 is a circuit diagram of an illustrative remote measurement sensor400. The remote measurement sensor 400 is merely one embodiment; othercircuits that measure similar parameters are contemplated. The remotemeasurement sensor 400 may include a battery 401 under test. Thepositive terminal 403 of battery 401 may be connected to a first node ofa resistive load 404 with a resistance value of Rt. The second node ofthe resistive load 404 may be connected to one contact of a switch 414,with the second contact of the switch connected to the negative terminal402 of battery 401. Switch 414 may be a single pole single throw switchand may open and close current flow from battery 401 across theresistive load 404. Switch 414 may be controllable such a FET switchimplementation, for example.

One node of a capacitor 413 may be connected to the positive terminal ofthe battery 401, the other node of the capacitor 413 may be connected tothe input of a voltage amplifier 412. The voltage amplifier 412,amplifies changes in voltage Vt measured at the positive terminal 403 ofthe battery 401 with respect to the negative terminal 402 of the battery401.

The output of the voltage amplifier 412 may be input to amicrocontroller 410. Microcontroller 410 may be a single-chipmicrocontroller and may include a built-in analog-to-digital converter.Microcontroller 410 may also include a dual-port optically isolatedserial communications interface with a first port 408 and a second port409.

Another aspect of this embodiment may include a diode 407. The anodeside of diode 407 may be connected both to the microcontroller 410 andthe positive terminal 404 of the battery 401. The cathode side of diode407 may be connected both to the microcontroller 410 and the first 408and second 409 communications interface ports. Diode 407 in thisarrangement may provide a summing function, such that when remotemeasurement sensor 400 is placed in a string with other like sensors,remote measurement sensor 400 may determine its position within thestring.

Another aspect of this embodiment may include a temperature sensor 406.The temperature sensor 406 may be a resistive load with a resistancevalue that is variable with temperature. A first node of the temperaturesensor 406 may be connected to a voltage regulator 405. A second node ofthe temperature sensor may be connected to both the microcontroller 410and the anode side of a diode 411. The cathode side of the diode 411 maybe connected to the negative terminal of battery 401. In thisarrangement, the DC voltage at the microcontroller is proportional totemperature measured by the temperature sensor 406.

The voltage regulator 405 provides DC power to the remote measurementsensor 400. One node of the voltage regulator 405 may be connected tothe positive terminal 403 of the battery 401. The other node of thevoltage regulator 405 may be connected to the temperature sensor 406,the voltage amplifier 412 and the microcontroller 410. The voltageamplifier 412 and the microcontroller 410 may also be connected to thenegative terminal 402 of battery 401.

The output voltage of amplifier 412, the voltage of temperature sensor406, and the voltages at both sides of the summing diode 407 may beinput to the analog-digital converter in the microcontroller 410. Eachvoltage may be measured, quantified, and used in the mathematical andlogical processes of characterizing the battery 401.

The microcontroller 410 may be programmed to close switch 414, causing atest current (It) to flow from the battery 401 across the resistive load404. The microcontroller 410, via an analog-digital converter, mayquantize an initial measurement of the voltage Vt measured between thepositive terminal 403 of battery 401 and the negative terminal 402 ofbattery 401. The microcontroller 410 then may open switch 414. Themicrocontroller 410 may measure voltage Vt again. Subtracting the secondmeasurement from the first, the microcontroller may calculate Vdelta1.Using Vdelta1 and the Randles battery model 100 discussed above, oranother battery model, the microcontroller may calculate a valuerepresentative of Rm 103.

The microcontroller 410 may be pre-programmed with a calibrationconstant that represents the value of capacitor 104 of the Randlesbattery model 100. The value of this constant may be determined from thetype of battery 401 being tested. The value of the capacitor 104 and thevalue of Rm 103 may be used to estimate the RC time constant of thebattery. Since RC circuits will generally discharge exponentially andstabilize within 5% of the final value in about 10 RC time constants,microcontroller 410 may wait for 10 RC time constants before talking athird measurement of the voltage Vt. Subtracting the third measurementfrom the second, the microcontroller 410 may determine a valuerepresentative of Vdelta2.

Microcontroller may measure Vdelta1 and Vdelta2 multiple times.Microcontroller may cycle switch 414 open and closed repeatedly with acycle time proportional to the measured RC time constant. This processof adaptive switching intervals allows the remote measurement sensor 400to make repetitive measurements at a speed that is optimum for thebattery 401 being tested.

Each Vdelta1 and Vdelta2 pair may be summed, and the resultant sums maybe averaged, producing a value Vtdelta. The values of Vtdelta, Rt, andthe pre-programmed calibration constant may be stored in themicrocontroller 410 and communicated to a site controller, for example,when the remote measurement sensor 400 is polled via the first port 408or the second port 409 of the communications interface.

FIG. 5 depicts an embodiment of a remote measurement sensor 400 fortesting a battery 501. The remote measurement sensor 400 may be packagedin sensor unit 500. The sensor unit 500 includes a first mounting tab504 and second mounting tab 505. The first mounting tab 504 may connectto the sensor unit via a 2-conductor wire terminated with a wire lug,for example. The second mounting tab 505 may extend from the body ofsensor unit 500. Each mounting tab may connect the sensor unit 500 tothe positive 502 and negative 503 terminals of battery 501 under test.In a preferred embodiment, the sensor unit 500 is mechanically andelectrically attached to the negative terminal 502 of a battery 501 bymeans of the second mounting tab 505. In the alternative, the sensorunit 500 could be designed for connecting the second mounting tab 505 tothe positive terminal 503. The sensor unit may be connected to the otherdevices, such as other sensors or a control unit, by one or morecommunications cables 505. The sensor unit 500 may measure the battery's501 terminal post temperature, terminal voltage, and other variablesthat are descriptive of the internal parameters of the battery. Theoperating power for sensor 500 may be obtained from the battery 501 towhich it is connected.

FIG. 6 shows two strings of batteries 607A-B being monitored by anexemplary remote battery monitoring system. Batteries 607A may beconnected in series to form a first battery string. Likewise, batteries607B may connected in series to form a second battery string. Eachbattery 607A-B in each string may be connected to a sensor unit 605A-B.Each sensor unit within the first string 607A may be interconnected viaa communications cable 604A. Likewise, each sensor unit within thesecond string 607B may be interconnected via a communications cable604B. Communications cables 604A-B may be four-conductor telephonecables or any other cable suitable for data transmission. Communicationcables 604A-B enable data communication between the sensor units 605A-Band a site control unit 602. This communication may be serial and/orparallel data communication. Strings of sensor units 605A-B may beconnected to the site control unit 602. The site control unit 602 mayinclude a number of interfaces 603 to support many communication cables604A-B and in turn many batteries 607A-B under test. The site controlunit 602 may be connected to a data network 601. The data network 601may be an Internet Protocol (IP) network or it may use another networkprotocol. The data network may employ T1, ISDN, DSL, broadband,Ethernet, WiFi, or other transport suitable for data transfer.

Each sensor unit 605A-B may test its respective battery 607A-B and maycommunicate data indicative of the battery's condition to the sitecontrol unit 602. This data may include, but is not limited to, valuesrepresentative of the overall voltage of the battery string, therelative position of the sensor unit within the string, the Vtdelta ofthe respective battery, the Rt of the respective sensor, and thecalibration constant pre-programmed in the respective sensor. The sitecontrol unit 602 subsequently performs mathematical calculations on thereceived data to report metrics indicative of battery condition. Thesite control unit may report the battery metrics via the data network601. It may provide an regular report via file transfer protocol (FTP),Hypertext Transport Protocol (HTTP), and/or another protocol. It mayprovide the metrics as requested or polled by a user or managementsystem via Simple Network Management Protocol (SNMP) or other protocol.The site control unit 602 may include a web server to display batterymetrics and to receive management controls.

Each sensor unit 605A-B within a string may determine the total voltageof the respective string of batteries 607A-B. This may be implementedvia circuitry related to diode 407 in each sensor. Within a string, eachsensor unit's cathode of diode 407 may sum the batteries voltages at adefined pin of the first 408 and second 409 interface port. The sitecontroller 602 may measure this voltage with respect to the string ofbatteries' overall minus voltage. The result is a overall voltage of thestring. The site controller 602 may report this voltage to all sensors605A-B within the string via a broadcast message over the communicationcable 604A-B.

Each sensor 605A-B may determine its relative position within therespective string of batteries 607A-B. This may be implemented viacircuitry related to diode 407 in each sensor. Within a string, eachsensor unit's cathode of diode 407 may sum the batteries voltages at adefined pin of the first 408 and second 409 interface port. Each sensor605A-B may measure this local voltage relative to the respectivebattery's minus voltage terminal 402. Each sensor unit 605A-B may dividethe measured local voltage by the overall battery string voltage,received from the site controller unit 602. The result is a valuerepresentative of the relative position of the sensor unit 605A-B. Onceeach sensor unit 605A-B determines its relative position within thestring, it may assume a logical address for purposes of communicationswith the site controller 602.

FIGS. 7A and 7B show a perspective view and an “x-ray” view of anexemplary sensor unit 700. The sensor unit 700 may include a thermallyand electrically conductive mounting tab 702. The mounting tab 702 mayprovide a mechanical, thermal, and electrical connection to a batteryterminal. For clarity, a second mounting tab for connecting to a secondbattery terminal is not shown in the figure. The mounting tab 702 mayextend from the sensor unit body 703. The body may be a housing made ofplastic or other material. The sensor unit body 703 may house the sensorcircuit 706. The sensor circuit may be a printed circuit board, abreadboard, or other physical implementation. The sensor circuit mayinclude a first 706 and second 707 parallel, optically isolated RJ-11jacks. Other electrical and optical jacks, such as RJ-45, LucentConnector (LC), and Ferrule Connector (FC), suitable for datatransmission may be used as well. Each may receive a respectivecommunications cable 704. Each communications cable 704 may enableinterconnection with other sensors as well as with the site controller602.

FIG. 8 depicts a perspective view of an exemplary site controller 602.The site controller may be contained in a housing 801. The housing 801may be suitable for containing electrical equipment and may be made ofmetal or plastic for example. The housing 801 may include one or moremounting features 802 for data center and telecom rack mounting, forexample.

The site controller 602 may provide one or more sensor interfaces 603 tointerconnect the site controller 602 with one or more communicationcables 604A-B. Each sensor interface 603 may be an RJ-11 jack; otherelectrical or optical jack, such as RJ-45, Lucent Connector (LC), andFerrule Connector (FC), suitable for data transmission may be used aswell. Each sensor interface 603 may include a data link light 808. Eachdata link light 808 may illuminate, flash, or change color to indicatethe status of the respective sensor interface 603. The data link light808 may be a light emitting diode or the like.

The site controller 602 may also include a network interface 805, suchas an RJ-45 Ethernet jack for example. The data interface may besuitable for T1, ISDN, DSL, broadband, Ethernet, WiFi, or other datatransport networks. The site controller 602 may include the appropriateinterface circuitry to enable the network interface 805.

The site controller 602 may include a program interface 806 such as anRJ-45 jack for example. The program interface 806 may be provided forthe purpose of connecting a portable computer directly to the sitecontroller for diagnostic tests, locally re-loading the operatingsoftware, locally loading configuration data, and other tasks. The sitecontroller 602 may include the appropriate interface circuitry to enablethe program interface 806.

The site controller 602 may include a power interface 804. The powerinterface 804 may enable connection to commercial AC power, via NEMA1-15 or NEMA 5-15 plug types for example. In the alternative, the powerinterface may enable connection to central office DC power, or any otherpower connection used in the alt.

FIG. 9 depicts a exemplary process 900 related to the operation andfunction of the sensor unit 605A-B. Each sensor unit 605A-B mayimplement the process 900 via the microcontroller 410, for example. Theprocess 900 may implemented in a software module or an applicationspecific integrated circuit. When each sensor unit 605A-B beginsoperation, the sensor unit 605A-B may initiate communication 901 withthe site controller 602. This initial communication 901 may includehandshaking or the like. Next, the sensor unit 605A-B may calculate itsrelative position 902 within the respective battery string. The sensormay use this relative position as a logical address for messaging withthe site controller 602. The sensor unit 605A-B may completeinitialization 903 and report that initialization is complete 904 to thesite controller 602. At this point, the sensor unit 605A-B may wait fora message 905 from the site controller 602.

Upon receiving a message, the sensor unit 605A-B determines 906 whetherthe message is destined for it or another sensor unit 605A-B. The sensorunit 605A-B may compare the address specified in the message with itsown logical address. If the addresses are different, the message isdestined for another sensor unit 605A-B. The sensor unit 605A-B maydiscard the message and return to waiting 905 for a message from thesite controller 602. If the addresses are the same, the message isprocessed 907 by the sensor unit 605A-B. The message may request thesensor to take measurements 909, to perform other processes, or toindicate that the site controller's address has changed 908. The sensorunit 605A-B will process the message appropriately. If the sitecontroller's address has changed, the sensor unit 605A-B may repeat theinitialization sequence 901. If the site controller's address has notchanged, the sensor unit 605A-B may wait 905 for another message fromthe site controller 602.

What is claimed:
 1. A battery sensor comprising: a. a voltage regulator;b. an electronic switch; c. a temperature sensor; d. an amplifier; e. ananalog to digital converter; and, f. a micro-controller; wherein: g. thevoltage regulator is adapted to receive power from a battery to bemonitored and is coupled to at least the micro-controller, the amplifierand the analog to digital converter to provide a regulated voltagethereto; h. the microcontroller is adapted to generate switchingcommands, for application to the electronic switch, according to aprogram; i. the electronic switch is adapted to receive the switchingcommands and to apply a stimulus to the battery in accordance with theswitching commands; j. the temperature sensor is adapted to measure atemperature of the battery and provide a temperature signal indicativethereof; k. the amplifier is adapted to receive a signal from thebattery in response to application of the stimulus, defining a responsesignal; l. the analog to digital converter is adapted to receive thetemperature signal and the response signal and provide digitalindications thereof to the micro-controller; m. there being informationin the sensor that is available when the sensor has been installed in aconnected string of batteries to be monitored that is useful todetermine a relative position of the sensor in the connected string ofbatteries, defining location information, wherein each sensor is adaptedto be associated with one of the batteries; and, n. the microcontrollerbeing further adapted to: (i) process at least the digital indication ofthe response signal according to the program; (ii) generate dataindicative of at least one condition of the battery; and, (iii) reportthe data indicative of the at least one battery condition and dataindicative of battery temperature and the location information.
 2. Thebattery sensor according to claim 1 wherein the location informationcomprises a signal obtained via a diode, the magnitude of which variesin accordance with the sensor's relative position in the string ofbatteries.
 3. The battery sensor according to claim 1 further comprisinga controller adapted to communicate with the sensor and to employ thelocation information to assign a relative position of the sensor in thestring of batteries.
 4. The battery sensor according to claim 1 whereinthe sensor includes the battery.
 5. The battery sensor according toclaim 1 wherein the sensor is adapted to be attached to an exterior ofthe battery.
 6. The battery sensor according to claim 1 furthercomprising a controller adapted to communicate with the sensor and toreport indications of battery condition to a remote monitoring location.7. The battery sensor according to claim 6 wherein the controller isadapted to transmit a command to the sensors to cause the application ofthe stimulus.
 8. The battery sensor according to claim 1 wherein theanalog to digital converter is integrated with the micro-controller. 9.A battery monitoring system, comprising: a. a plurality of sensors, eachsensor comprising: i. a voltage regulator; ii. an electronic switch;iii. a temperature sensor; iv. an amplifier; v. an analog to digitalconverter; and, vi. a micro-controller; wherein each sensor is adaptedto be associated with a particular battery in a string of batteries tobe monitored, and further wherein: vii. the voltage regulator of eachsensor is adapted to receive power from its respective battery and iscoupled to at least the micro-controller, the amplifier and the analogto digital converter to provide a regulated voltage thereto; viii. themicrocontroller of each sensor is adapted to generate switchingcommands, for application to the electronic switch, according to aprogram; ix. the electronic switch of each sensor is adapted to receivethe switching commands and to apply a stimulus to its respective batteryin accordance with the switching commands; x. the temperature sensor ofeach sensor is adapted to measure a temperature of the battery andprovide a temperature signal indicative thereof; xi. the amplifier ofeach sensor is adapted to receive a signal from its respective batteryin response to application of the stimulus, defining a response signal;xii. the analog to digital converter of each sensor is adapted toreceive the temperature signal and the response signal and providedigital indications thereof to the micro-controller; xiii. there beinginformation in each sensor that is available when the sensors have beeninstalled in the string of batteries that is useful to determine arelative position of each sensor in the string of batteries, defininglocation information; and, xiv. the microcontroller of each sensor beingfurther adapted to: (i) process at least the digital indication of theresponse signal according to the program; (ii) generate data indicativeof at least one condition of the battery; and, (iii) report the dataindicative of the at least one battery condition and data indicative ofbattery temperature and the location information; and, b. a controlleradapted to communicate with each sensor and to report informationindicative of conditions of each battery to a remote monitoringlocation.
 10. The battery monitoring system according to claim 9 whereineach sensor includes its respective battery.
 11. The battery monitoringsystem according to claim 9 wherein each sensor is adapted to beattached to an exterior of its respective battery.
 12. The batterymonitoring system according to claim 9 wherein the controller is adaptedto employ the location information to assign a relative position of thesensor in the string of batteries.
 13. The battery monitoring systemaccording to claim 9 wherein each sensor further comprises a diodecoupled to provide a voltage that varies in accordance with the sensor'srelative position in the string of batteries, the voltage being thelocation information.
 14. The battery monitoring system according toclaim 9 wherein the controller is further adapted to communicate batterycondition information to a remote monitoring location.
 15. The batterymonitoring system according to claim 9 wherein the controller is adaptedto transmit a signal to each sensor to cause the application of thestimulus.
 16. The battery monitoring system according to claim 9 whereinthe analog to digital converter is integrated with the micro-controller.17. A method of monitoring the condition of each battery in a connectedstring of batteries comprising, for each battery: a. generating aregulated voltage via a voltage regulator and the battery beingmonitored; b. providing the regulated voltage to an analog to digitalconverter, an amplifier and a micro-controller; c. generating a batterytemperature signal via a temperature sensor; d. causing themicro-controller to generate switching commands according to a program;e. applying the switching commands to an electronic switch; f. applyingvia the electronic switch a stimulus to the battery in accordance withthe switching commands; g. receiving via the amplifier a response signalfrom the battery; h. providing information useful to determine arelative position of the battery in the string of batteries, defininglocation information; i. providing the battery temperature signal, thelocation information and the response signal to the analog to digitalconverter; j. causing the analog to digital converter to provide digitalindications of the battery temperature signal, the location informationand the response signal; and, k. causing the micro-controller to (i)process at least the digital indications of the response signalaccording to the program; (ii) generate data indicative of at least onebattery condition; and (iii) report the data indicative of the at leastone battery condition and data indicative of battery temperature and thelocation information.
 18. The method of claim 17 further comprisingproviding the data indicative of the at least one battery condition anddata indicative of battery temperature and the location information to acontroller and causing the controller to communicate indications ofbattery condition to a remote monitoring location.
 19. The methodaccording to claim 17 further comprising, at the controller, using thelocation information to assign information indicative of a relativelocation of each battery in the string.
 20. The method according toclaim 17 wherein (a) through (k) are carried out in a sensor, and thesensor includes the battery.